Field of the Invention
The present invention relates to a processing method of a seal mounting groove in a metal plate, that is, a method for processing a seal mounting groove on a plane of a metal plate. The metal plate is, for example, used as a separator which is a cell component part of a fuel battery.
Description of the Conventional Art
For future diffusion of the fuel battery, it is necessary to downsize the cell component parts such as the separator and the gasket, make them be easily manufactured and make costs thereof low. In order to respond these demands, for example, a separator integrated seal is hopeful, the separator integrated seal being obtained by integrally molding a gasket constructed by a rubber-like elastic body directly in a separator constructed by a metal plate. However, employment of the separator integrated seal mentioned above is on condition that it is necessary to make study of easily manufacturing the separator itself and achieving a low cost.
FIG. 4 shows an example of a separator 11 which is constructed by a metal plate, and a gasket 21 is integrally formed on a plane of the separator 11 so as to surround a periphery of a power generation area 12 and so as to surround a periphery of each of manifold holes 13 (refer to Japanese Unexamined Patent Publication No. 2011-96545).
Further, as shown in FIG. 5, a seal mounting groove 14 for mounting a gasket 21 is formed on the plane of the separator 11 in conformity to arrangement of the gasket 21, and the gasket 21 is generally formed integrally in a groove bottom portion 14a of the seal mounting groove 14.
A cutting method is provided as a method of forming the seal mounting groove 14 on the plane of the separator 11 which is constructed by the metal plate.
However, the cutting method has a good processing precision, however, has a problem that the processing cost is high.
Further, a pressing method is provided as a method of forming the seal mounting groove 14 on the plane of the separator 11 which is constructed by the metal plate, and the pressing method forms the seal mounting groove 14 on the plane of the separator 11 on the basis of a strong pressure by a punch 31, as shown in FIGS. 6A to 6C. The punch 31 is frequently provided as a part of a press mold.
However, since a leading end portion 31a of the punch 31 is conventionally formed into a flat shape which is in parallel to the surface 11a of the separator 11 as shown, the pressing pressure is dispersed. As a result, the seal mounting groove 14 having a predetermined depth can be formed only by applying an extremely great pressing pressure.
Further, since the metal which plastically deforms going with the formation of the seal mounting groove 14 protrudes in shoulder portions in both right and left sides of the seal mounting groove 14 (the protruding portion is shown by reference numeral 15), there is a risk that a plane area of the power generation area 12 which can normally function becomes narrower due to the protruding phenomenon. Further, in the case of carrying out a drawing process for crushing and flattening the protruding portion 15, the protruding portions 15 in both the right and left sides can be crushed and flattened only by applying the great pressing pressure.